Cream of Crab Soup

In medium bowl, blend flour, Hollandaise sauce mix, and dry mustard with two cups of half-and-half. Melt butter over medium heat in a 4-quart saucepan. Slowly add above mixture to melted butter, stirring constantly to ensure smooth consistency. As mixture begins to thicken, add remaining half-and-half, Old Bay seasoning, celery seeds, and whipping cream. Heat to simmer, stirring constantly. Reduce heat to low, add crab meat and sherry. Stir gently until heated through, and serve. Top each bowl with freshly ground pepper to taste.